Photo Gallery: Big Cats

Three female lions and a pair of cubs rest in the grass in Botswana's Okavango Delta. Females remain with a pride for life and often have to defend their cubs from males, who will kill young lions when taking over another male's territory.

National Geographic is working to avert the lions' extinction with the Maasailand Emergency Fund. Donations will be used to support animal husbandry education and job creation for the Maasai, among other endeavors.